Mycobacterium chimaera (M. chimaera) is a non-tuberculous mycobacterium of the Mycobacterium avium complex. Between 2013 and April 2018, more than 140 cases of severe infection have been identified, all of them in patients who had undergone cardiothoracic surgery with extracorporeal circulation. The epidemiological investigations have shown that the majority of infections have a common source: contaminated normo-hypothermia modules. These devices have a water circuit inside and cooling fans that produce an aerosol, which can be contaminated with M. chimaera, and disperse it into the air in the operating room. The clinical symptoms can take months, even years to appear after the extracorporeal surgery, with an average of 1.5 years. Sarcoidosis is the most frequently described entity as a misdiagnosis in these patients, so it is necessary to maintain a high diagnostic suspicion in all patients with a history of cardiac surgery with extracorporeal circulation.